A keyboard is an indispensable device when people use a computer nowadays. A user presses a plurality of keys provided on the keyboard to input instructions. Referring to FIG. 1, FIG. 1 is a schematic sectional view of a conventional function key. In most cases, the keyboard has a function key 9. The function key 9 here is, for example, a Caps-Lock key, and an indicator light 91 is provided below the function key 9. Light of the indicator light 91 passes through a keycap 90 of the function key 9 to remind a user of a current state of the function key 9. Further, the indicator light 91 is turned on when the function key 9 is pressed for the first time, and the indicator light 91 stays on after the function key 9 is released to remind the user that the function key 9 is currently in a first state. When the function key 9 is pressed again, the indicator light 91 is turned off to remind the user that the function key 9 is currently in a second state.
Specifically, the keycap 90 of the function key 9 has a light hole 905, so that the light of the indicator light 91 located below the function key 9 is emitted upward to pass through the light hole 905. However, in a current architecture of the function key 9, to prevent a structure of the function key 9 from blocking the light of the indicator light 91 from upward radiation, the function key 9 needs to be made wider to provide space in the transverse direction. That is, below the keycap 90, the space on one side (for example, the left side) is occupied by a key mechanism 92. The space on the other side (for example, the right side) needs to be reserved for the light of the indicator light 91 to pass through, and as a result no element can be disposed here. That is, it needs to be avoided to arrange the indicator light 91 right below the key mechanism 92. Therefore, the function key 9 occupies a relatively large transverse area and consequently affects the arrangement of all keys of the keyboard. In view of the above, the conventional function key 9 still needs to be improved.